The Brazilian authorities are investigating the deaths of at least 21 people, thought to have been caused by a contaminated drug.
Celobar is used in x-ray and other tests
The patients died after being given a Brazilian brand of a dye called Celobar - which is sometimes used in radiology examinations.
In a separate case, government inspectors are blaming hospitals for using a gel in eye operations, which resulted in five patient becoming blind.
Doctors are demanding tighter controls of locally-produced medicines.
In the investigation into Celobar, police and health authorities say lethal levels of a toxic ingredient were found in a number of patients who died after being given the drug.
In total, the product is thought to have caused 21 deaths in different parts of Brazil.
Celobar is a dye used before X-ray and other tests.
Its main active ingredient is barium sulphate, which is derived from the highly toxic substance barium carbonate.
Brazilian inspectors say only handful of foreign laboratories are able to produce barium sulphate safely.
The company in Rio de Janeiro which manufactures the Brazilian version, they add, does not have the technical capacity to do so.
The company's executives have been barred from leaving the country.
In the case of the eye gel, more than a dozen patients developed serious infections after operations and five of them became blind.
Health inspectors say the gel is a cheap counterfeit produced by an unlicensed laboratory.
Brazilian doctors have called for tighter government controls on medicines.
They also say there should be less pressure from insurance companies to use cheap drugs to keep down costs.